Dam those fish: human-environment interaction on the Androscoggin River

Jenny IbsenAny north-facing windows at Fort Andross provide a full view of the Brunswick dam, a massive concrete structure on the Androscoggin River with a capacity 19,000 kilowatt-hours, according to the Maine Governor’s Energy Office. Today’s dam is hydroelectric, owned by Brookfield Renewable, a subsidiary of the international asset management company, but dams have shaped Brunswick’s development for centuries—the first was built in 1753 to serve the town’s sawmills.

Although dams sparked Brunswick’s economic development, they haven’t been as kind to the fish that inhabit the Androscoggin. Migratory fish find it difficult to circumvent dams, making it difficult to reach their spawning grounds up river.

Professor of Biology and Environmental Studies John Lichter is well-versed in the river’s history.

“The first dam in Brunswick was in 1753. Now people back then knew that if they didn’t let the fish get by, they would lose the fish, and they needed the fish. And so there was a river warden appointed who would just say, ‘It’s time to let the alewifves through. It’s time to let the shad through,’” Lichter said.

While Brunswick’s original dam was made from natural materials, later dams were constructed out of concrete, eliminating the possibility for fish to move upstream. As the centuries progressed, other environmental harms proved just as detrimental.

“Dams were the first thing, then land clearance, then the pollution from industry in the twentieth century was off the charts. Raw sewage. Fish didn’t like that either,” Lichter said.

The same textile and paper mills that powered Brunswick’s growth proved disastrous for its fish. By the 1930s, the Androscoggin’s population of sea-run fish was virtually gone, according to the Maine Department of Marine Resources (DMR). Still, with time and intensive pollution abatement efforts, populations began to return in the 1970s.

In the 1980s, the DMR introduced a fish restoration program in the Androscoggin. Complementing these efforts in 1982, Central Maine Power added a new concept to the dam—a fish ladder, designed to help species cross over the dam so they could continue their spawning patterns further upstream.

The fish ladder and a viewing room are open to the public during the summer, giving visitors the chance to see some fish migration in action. Unfortunately, the effectiveness of the ladder is hotly contested. Lichter’s research has shown that the ladder only helps a few fish species.

“It doesn’t work at all for shad,” Lichter said. “Very few shad get up there, numbering a few dozen.”

Meera Prasad ’19 spent last summer studying shad movements on the Androscoggin. While her sonar instruments documented several thousand shad each day below the dam, DMR employees and volunteers observed only one shad make it to the top of the river ladder.

Lichter has found that the ladder is effective only for alewives. He noted that salmon are sometimes able to make it up the ladder, but are often beaten or injured along the way.

Since technology has improved since the fish ladder was constructed nearly 40 years ago, Lichter is hopeful that changing the mechanism could help fish populations. He suggested a fish elevator, which would essentially bring up fish in a bucket in certain time intervals, as a potential alternative.

In the present moment, there remains little impetus for change. The lease on the Brunswick dam will come up in 2029, at which point the fish ladder—as well as other aspects of the dam—may be reevaluated.

“It would mean less fish would be getting beat the hell on the side walls—you can quote me on that,” Lichter said.